Converting residuum into charging stock and coke



Oct. 19, 1937. F. c. KOCH 2,096,589

CONVERTING RESIDUUM INTO CHARGING STOCK AND COKE Filed July 10, 1933 TOTORAGE Z! PRESSURE PRESSURE DISTILLATE 44 OUTLET HEATING PRESSUREfive/7257? di MW. A/ [k g;

Patented Oct. 19, 1937 PATENT OFFICE CONVERTING RESIDUUM INTO CHARGINGSTOCK AND COKE Fred C. Koch, Wichita, Kans., assignor to The WinklerKoch Patent Company, ,Kans a corporation of Kansas Wichita,

Application July 1 0, 1930, Serial No. 467,026

11 Claims.

The present invention relates to a process and apparatus for convertingpetroleum products, containing a preponderance of heavy ends, into coke,with the concomitant production of a clean 1 distillate suitable for useas a cracking stock.

One of the objects of the invention is to convert residuum from oilcracking operations into merchantable petroleum coke and into adistillate which may be used as a clean charging stock for an oilcracking system.

A further object of the invention is to treat heavy residuum in asuitable container with a very highly heated cracked petroleum productwhereby the heat of said cracked petroleum product will be imparted tothe residuum with the result that the residuum is highly heated so as tocause the volatilization therefrom of all of the lighter ends thereincontained, the heat being sufiiciently high to convert the residuum into2Q petroleum coke.

A further object of the invention is to inject highly heated crackedpetroleum products into a body of oily residuum so as to heat theresiduum to a coking temperature while .maintaining above the body ofsaid residuum a pressure low enough to cause substantially completevolatilization of all volatile matter therein contained, as well as toinsure the volatilization of all volatile products introduced into theresiduum by the heated cracked petroleum products. 7

A still further object of the invention is to heat heavy residuum by theintroduction thereinto of very highly heated petroleum products drawnfrom the discharge end of an oil cracking still, under such conditionsthat the volatilematerial in said petroleum products as well as theresiduum treated thereby may freely volatilize, whereby a final residueof petroleum coke is obtained and a distillate produced which may beintroduced as of said apparatus to an entire operative oil crack--' aclean charging stock into the oil cracking sysing system. Obviously theinvention is not limited to the particular cracking system illustratedand described but is applicable to any system in' which a residuum isproduced that may be con verted into lighter ends adaptable for chargingstock and in which the heavier ends can be converted into coke.

The present invention comprises essentially the treatment of residuum inone or more unheated stills by means ofhighly heated crackedproductsdrawn directly from the discharge end of an oil cracking still,which products are introduced into abody of said residuum. The volatileproducts resulting from the heating of said residuum by said petroleumproducts are discharged from the upper portions of said otherwiseunheated stills and are condensed to form a distillate suitable for useas a clean charging stock for introduction into oil cracking systems.

In the operation of an oil cracking system, a quantity of a heavy oilgenerally known as re-' siduum is produced. This residuum is usuallydischarged from the system without further treatment and frequently issold as fuel oil.

The price of said fuel oil varies from time to time and it often occursthat the price of said fuel oil is so low that its profitable sale isprecluded. Under such conditions, it becomes more economicaltotreat theresiduum to obtain there from lighter ends, Which can be used ascharging stock for the cracking unit, and reducing the heavier ends tocoke which can be sold as such on, the market.

It has been customary to convert such residuum into cokeby charging thesame into an ordinary shell still, heated directly-by the combustion ofa suitable fuel whereby the residuum in said shell still is highlyheated so as to distil the Vela-- tile parts thereof leaving a finalresidue of petroleum carbon. The shell still was'then allowed to cooldown and the-carbon or coke removed therefrom, after which a freshcharge of residuum is charged to the still and the operation repeated.

The present invention avoids the use of a separately heated still inthat the residuum is heated by using a portion of the hot crackedmaterial as it emerges from the cracking still which is introduced intoa container into which the residuum is discharged. l j

The residuum-treating stills or containers are so'coordinated with thebalance of the cracking. equipment, that: the operation may be so can--ducted that the residuum may either be drawn off as such or may beconverted into coke and clean 'charging stock attheoption of theoperator by the simple expedient of the setting of certain valves andthe operation of various pumps and condensers.

In order that the invention may be properly understood, and, withreference to the aforementioned drawin illustrating a preferred form ofthe invention, the operation of an oil cracking unit of the type towhich the present invention is applicable, will now be given:

The illustrative oil cracking unit consists of a pipe still 2 heated byany suitable source of heat, such as a burner 3 and contains acontinuous cracking coil 4 through which the oil to be cracked is forcedunder pressure, this pressure being controlled by the valve I. The oilenters the cracking still through the pipe 5, being forced into saidpipe by means of the pressure pump 6 and flows in the directionillustrated by the arrows on the drawing. The temperature of the oilincreases as it flows through the cracking coil 4 in which it will verysoon reach the cracking temperature,

and this cracking will continue from there on through the coil, thetemperature of the oil and/or vapors as they leave the coil preferablybeing somewhere around 900 F. The cracked oil is discharged from thecracking coil 4 through a transfer line 8 provided with the expansionvalve I, at which point pressure in said oil is materially reduced, as,for example, from 600 pounds to 200 pounds or from 60 pounds to 30pounds, depending upon the desired operation of the system.

This reduction in pressure, at the given temperature, will result in thecomplete volatilization of all the volatilizable products in the oilbeing treated provided such complete volatilization has not alreadyoccurred in the cracking coil. Just beyond the expansion valve I is abranch pipe 4' through which heavy oil is introduced into the recentlyexpanded cracked products. This heavy oil is heated by the crackedproducts and a con siderable portion thereof is volatilized, the mixedproducts being discharged into the vapor separator 9. The vapors in thevapor separator are fed through pipe 29 into the lower part of asuitable dephlegmator well known to those skilled in the art, and fromthe upper end of this dephlegmator the desired vapor ends are conductedthrough pipe 35 to a suitable condenser 36, and thence through pipe 37through a separator 38. From the separator 38 the uncondensable gasesare drawn off through the pipe 39 under the control of the valve 39 andthe pressure distillate is withdrawn through the pipe 43 under thecontrolof the valve 44. All of the heavy vapors which are not desirablefor conversion into pressure distillate are knocked down in thedephlegmator 32, as well known tothose skilled in the art, and thisreflux accumulating in the dephlegmator is withdrawn throughthe pipe 34and is charged into the pipe through the pressure pump 6 and fed to thecracking coil as heretofore described.

It will be evident from the foregoing description that intermingling ofthe heavy oil. feed with the heated cracked products just beyond theexpansion valve I results in a stripping action of said heavy oil feedwhereby the desired portion of said heavy feed suitable as cleancharging stock will be vaporized and carried with the vaporized crackedproducts through the line 29 into the dephlegmator 32, and that thoseconstituents of, these vapors not suitable for pressure distillate willbe knocked down in'the dephlegmator as reflux and charged to thecracking still as hereinbefore described.

If the clean charging stock thus produced is not suflicient toadequately supply the cracking unit, then additional clean stock issupplied to the dephlegmator from a storage (not shown) by way ofpressure pump 4! and pipe 40 which discharge this stock into the upperportion of the dephlegmator 32, where this charging stock is heated bythe rising vapors and also acts as a refluxing medium to strip thesevapors of their heavier ends. This clean charging stock thus introducedinto the dephlegmator, together with the reflux, is charged through thecracking still as hereinbefore outlined.

The mixture of cracked products and heavy oil feed entering the vaporseparator are therein separated into the vapors which are carried overinto the dephlegmator, ashereinbefore described, and

intoa liquid which collects at the bottom of the vapor separator, andwhich is ordinarily referred tion of the system is so conducted that theresiduum contains a large proportion of ends which might be used ascharging stock, then it may be desirable not to dispose of said residuumas commercial fuel oil, but to retreat said residuum and convert it intoa charging stock and coke, the charging stock being returned tothesystem and the coke being sold as a commercial product.

This invention is directed in part to an im proved and novel process forconverting this residuum into coke and charging stock. If it is notdesired to withdraw the residuum as such from the vapor separator, thenit is conducted through the pipe It to either one of the tanks or stillsI3 or I4 by way of the valves I I and I2, respectively. These tanks I3and I4 are alike and are supplied in duplicate so that the process maybe conducted in one of said tanks while the other tank is being cleaned,that is, having the coke formed therein removed therefrom. The tanks areprovided with suitable manhole openings I3 and I4 for the removal of thecoke. Since the operation in either one of these tanks would beidentical, the description in the following will be confined to the tankI3, under which circumstances valve II will be opened and valve I2closed.

The residuum from the vapor separator under these conditions will flowthrough line I0, valve GI being open, and valves 5|, 62 and 63 beingclosed, through valve II, which is open, into the tank I3. At the sametime valve will be opened to permit a desired portion of the crackedproduct to flow through pipe 24, and thence through pipe 26 and valve26', which is open, into the bottom of tank I3. This hot, crackedproduct, having a temperature somewhere around 900 R, will mix with theresiduum fed to the tank I 3, and since the pressure in thetank I3 issubstantially at atmospheric, excessive volatilization will occur insaid tank. The vapors in said tank will flow through valve 64, which isopen, and line I5 intothe condenser I6, and thence by way of valve 65,which is open, into the separator I8, the valve I? being closed.

In theseparator I8 the uncondensable gases will flow through pipe I9 andvalve IE! to a suitable storage, whereas the condensed products willflow from said separator I8 through pipe 20 and pressurepump 2| throughvalve 20', which J pheric pressure.

is open, and line 22 and valve 69, which is open, into the transfer line8, where it will comingle with the cracked products after they have beenexpanded beyond valve "I and with the heavy oil feed, which isintroduced into the transfer line 8 just beyond. The mixture of theseproducts'will flow into the vapor separator 9 where the vapors willleave by way of the pipe 29, as hereinbefore described, and the residuumwill be drawn off through the pipe IE to be again treated ashereinbefore described.

When the treatment of the residuum in tank I3 has continued for asufiicient period, so that considerable coke has collected in the tankI3, then the valve H is closed and valve I2 is opened and the residuumwill then be drawn into the tank I4. Under these circumstances the valve26' will be closed and the valve 2? opened and the hot cracked productswill flow from line 24 through line 27 and valve 21' into the tank I4.The treatment of the residuum by the hot cracked products will then takeplace in the tank I4 in the same manner as hereinbefore described inconnection with tank I3.

During the period that the residuum is being treated in tank I4 theoperators will remove the coke from tank I3 and when sufficient coke hascollected in tank I4, tank I3 will again be ready for operation and thevalves will be operated so as to carry the residuum and cracked productsinto tank I3 in place of tank I4. This operation will be alternatedbetween tanks I3 and I4, so as to have a continuous operation of thetreatment of residuum by the cracked products, whereby the heat of thecracked products will volatilize the residuum, stripping it to coke, thestripped products being carried by way of the line I and condenser It tothe separator i8, as hereinbefore described.

In the event that the temperature of the cracked products is notsufliciently high toreduce the residuum to coke in the tanks or stillsl3 and I4, or if it is desired to reduce the amount of the crackedproducts which is utilized for this operation, it might be desirable tosubject the residuum to a heating operation before it is con ducted intothe tank I3. For this purpose a heating coil 60 is illustrated which isconnected into the pipe [9 by means of valves 62 and 63. If the residuumis to be heated before entering the tanks I3 or I4, the valve SI isclosed and the valves 62 and 63 are opened, under which circumstancesthe residuum will flow through pipe l0, through valve 62, the heatingcoil 60, valve 63, and then back into pipe [5, and thence to the tanksI3 or [4, depending upon the setting of the valves in the system.

The vaporization of the residuum may also be augmented by theintroduction of steam into the pipe I0, and for this purpose the steampipe 61 is shown connecting into the pipe II], the introduction of steambeing regulated by the valve 68. For increasing the vaporization of theresiduum products either the heating coil 66, or the introduction ofsteam, or both, may be utilized. If steam is used provision must be madein receiver I8 to separate the stratified lighter oil produced from thelower layer of water which will form therein as is well known to thoseskilled in the art, no special provision for this purpose being shown inthe drawing.

In order to assist and accelerate the coking action in the tanks I3 andI4, it might be desirable to operate the tanks I3 and I4 at a sub-atmos-For this purpose thevacuum pump I I is provided which may be connectedinto the'pipe line leading from the tanks I3 and I4 by opening the valveI! and closing the valve 65. Under these conditions the pipe I5 will beconnected through the condenser I6 and the valve I! to the vacuum pumpI'I', said pump being connected to the separator [8 by the pipe 66.

As is well known to those skilled in the art a coking operation isaccelerated by increased heating of the product being treated and alsoby reduction of pressure on the material that is being treated.Consequently, depending upon conditions and the results desired, theprocess and apparatus hereinbefore described is arranged so that thecoking operation in the tanks or stills I3 and I4 can be conductedeither by one of three methods. First, by treating the residuum merelywith the cracked products withdrawn from the transfer line 8 at apressure'substantially at, at-

mospheric; second, by treating the residuum with the hot crackedmaterial withdrawn from the transfer line 8 under sub-atmosphericpressures, and, third, by treating the residuum with the hot crackedproducts withdrawn from the transfer line 8 at either. substantialatmospheric or subatmospheric pressure and by preheating said residuumin the coil 60, or with steam, or both, before discharging it into thetreating tank I3 or I4.

Which one of these methods would be most suitable will depend upon localconditions and can be readily determined by those skilled in the art,depending upon the manner in which the coking operation proceeds in thetanks I3 and I4.

It will be evident from the foregoing description that in the improvedprocess described herein the residuum which is withdrawn from the vaporseparator can be either sold as such, generally as fuel oil, ifcommercial conditions warrant such sale. However, if the demand for fueloil is inadequate, or if the residuum contains a large percentage ofmaterial that may be charged to the cracking system for the productionof pressure distillate, then said residuum can be eco nomically treatedin the tanks I3 and I4 by reducing the residuum to coke and rechargingthe volatilized constituents of said residuum produced as a result ofthe coking operation to the cracking system.

The product which is formed as a result of the coking operation in thetanks I3 and I4 will depend upon the nature of the residuum formed inthe vapor separator and the manner in which the coking operation isperformed in the tanks I3 and I4. If the residuum is of a suitablecharacter and the coking operations in the tanks I3 lected in theseparator I8 for recharging to thev system is a clean stock, then saidstock may be pumped'by the pressure pump 2| through the line 22 and thevalve 61, valve 69 being closed, into the line 40, to be fed into thedephlegmator with the fresh clean stock which is pumped into thedephlegmator from storage, as hereinbefore described.

If, however, the product collecting in the separator I8 is not a cleanstock but contains material which might tend to carbonize and coke inthe cracking pipe 4, then the valve 61 should-be closed and the valve 69opened, and this material returned to the transfer line 8 to beintermingled with the cracked charging stock and the heavy oil feed, ashereinbefore described. Under these conditions the clean ends of theproduct charged into the transfer line coming from the separator I8 willbe vaporized in the same manner as the heavy oil which is charged intothe transfer line through line 4, and these volatilized ends will becarried from the vapor separator through the line 29 into thedephlegmator where they will be refluxed and returned to the crackingcoil through the line 3 5, pressure pump 6 and line 5.

The essential and novel feature of this invention resides in the use ofhighly heated cracked products for effecting the coking of residuum inan otherwise unheated coking still with simultaneous condensation of thevolatile matter thus produced and the introduction of the resultantcondensate into the system either directly into the transfer lineleading from the cracking unit to the vapor separator or, if theresulting conadjustment of a few valves, the residuum may either bewithdrawn from the system to be sold as a commercial product; or it maybe reduced to coke and the volatilized portions of the residuum returnedto the system for further treatment.

These alternate operations can be performed with an apparatus of simplecharacter requiring an initial minimum cost, as well as a minimumoperating cost.

While this invention has been described in connection with anillustrative type of cracking systems, it is obvious that it isapplicable to other types of cracking systems in which it is desirableto treat residuum with highly heated cracked products, so as to heat thesame to the coking temperature. and with the simultaneous removal of allvolatile matter from the said cracked products and residuum for theformation of a condensate which can be recharged to the cracking system.

What is claimed and desired to be protected by Letters Patent is:

1. The process of treating petroleum products which consists in passinga clean feed oil through a pipe still heated to a cracking temperatureand under superatmospheric pressure, passing the cracked productsthrough an expansion valve, introducing a heavier feed oil into saidproducts, and passing the resulting mixture into an enlarged zonewherein vapors separate from unvaporized residuum, removing said vaporsfrom said enlarged zone, continuously transferring said residuum fromsaid enlarged zone to a still wherein it is vaporized, withdrawing thevapors from said still and condensing them, and mixing the result ingcondensate with the cracked products immediately after the latter havepassed through the expansion valve.

2. The process of converting oils into gasoline and petroleurn cokewhich comprises heating a continuously advancing oil stream in a heatedpipe still to cracking temperature under pressure, passing the heatedproducts through an expansion valve into an enlarged space, separatingthe resultant volatile products and non-volatile products in said spaceand conducting the volatile products to a dephlegmating tower and thenonvolatile products to a tank still, returning the condensate from thedephlegmating tower to the pipe still, diverting a portion of the highlyheated cracked products from the outlet of said pipe still to said tankstill and allowing said cracked products to pass into the non-volatileproducts therein whereby coke and condensable vapors are formed,condensing said vapors and transferring the resultant distillatedirectly to said enlarged space in admixture with freshly expandedhighly heated cracked products.

3. The process of converting oils into gasoline and petroleum coke whichcomprises heating a continuously advancing oil stream in a heated pipestill to cracking temperature under pressure, passing the heatedproducts through an expansion Valve into an enlarged space, separatingthe resultant volatile products and non-volatile prod ucts in said spaceand conducting the volatile products to a dephlegmating tower and thenonvolatile products to a tank still, returning the condensate from thedephlegmating tower to the pipe still, diverting a portion of the highlyheated cracked products to said tank still and allowing said crackedproducts to pass into the non-volatile products contained thereinwhereby coke and condensable vapors are formed, condensing said vaporsand transferring the resultant distillate to the said dephlegmatingtower.

4. The process for converting petroleum products into gasoline and coke,which comprises heating the petroleum products in a pipe still to acracking temperature under superatmospheric pressure, then reducing saidpressure and introducing a heavier hydrocarbon oil into said crackedproducts, separating the resulting mixed product into a residuum andvapors, subjecting the said vapors to dephlegmation to separate thedesired lighter end vapors from a liquid reflux, returning said refluxto said pipe still for further cracking and condensing said separatedlighter end vapors, collecting said residuum in a suitable container orstill, withdrawing a stream of said cracked petroleum products prior totheir admixture with the heavier hydrocarbons from the main stream ofsuch products leaving the pipe still and mixing the same with saidresiduum collected in said container or still, whereby the lighter endsof said residuum will be vaporized and the heavier ends reduced to cokeby the contained heat of the said cracked petroleum products, condensingthe said vaporized lighter ends of Said residuum, and returning the saidcondensed lighter ends or" said residuum into said cracked petroleumproducts.

5. The process for converting petroleum products into gasoline and coke,which comprises heating the petroleum products in a pipe still to acracking temperature under superatmospherlc pressure, then reducing saidpressure and introducinga heavier hydrocarbon oil into said products,separating the resulting mixed product into a residuum and vapors,subjecting the said vapors to dephlegmation to separate the desiredlighter end vapors from a liquid reflux, returning said reflux to saidpipe still for further cracking and condensing said separated lighterend vapors, collecting said residuum in a suitable container or still,withdrawing a stream of said cracked petroleum products prior to theiradmixture with the heavier hydrocarbons from the main stream of suchproducts leaving the pipe still and mixing the same with said residuumcollected in said container or still, whereby the lighter ends of saidresiduum will be vaporized and the heavier ends reduced to coke by thecontained heat of the said cracked petroleum products, condensing thesaid vaporized lighter ends ofsaid residuum, and returning the saidcondensed lighter ends of said residuum into said cracked petroleumproducts before their admixture with the heavier hydrocarbon oils.

6. The process of producing gasoline and coke from petroleum whichcomprises feeding a petroleum product successively through a highpressure cracking zone, a separating zone and a dephlegmating zone .andreturning dephlegmated condensate to said cracking zone, withdrawingheavy products from said separating zone and passing them to a zonewhere coke and vapors are formed, condensing said vapors to a liquid andpassing the latter directly to the separating zone, and diverting aportion of the products from said high pressure cracking zone to saidcoking zone.

7 The process of cracking petroleum to produce gasoline and coke whichcomprises the steps of' passing petroleum products through a highpressure cracking zone, dividing the high pressure cracked products thusproduced into two streams, one of which passes into an enlargedseparating zone in which separation into lighter and heavier products isefiected, the heavier products being transferred to a coking zone, thesecond high pressure stream being directed into said coking zone to aidin converting said heavier products into coke and a distillate, saiddistillate being admixed with said first high pressure stream passinginto said separating zone.

8. The process of converting heavy petroleum into gasoline and cokewhich comprises the steps of heating the petroleum to crackingtemperature while passing through a high pressure cracking zone,releasing said pressure and passing the resulting cracked products intoan expansion zone Where vapors and liquid residuum are separated,transferring said residuum to a tank still, diverting a portion of thecracked products passing from said high-pressure cracking zone into saidtank still under reduced pressure to distill said residuum and toproduce coke, condensing the resulting vapors and returning saidcondensate directly to said expansion zone.

9. The process of cracking petroleum to produce gasoline and coke whichcomprises the steps of passing petroleum products through a highpressurecracking zone, dividing the cracked products thus obtained into twostreams, one of which passes into an enlarged separating zone in whichseparation into lighter and heavier products is effected, the heavierproducts being transferred to a coking zone and the lighter products toa dephlegmating zone, the second stream being directed into said cokingzone to aid in converting,

said heavier products into coke and a distillate, and transferring saiddistillate to said dephlegmating zone.

10. A hydrocarbon oil cracking process which comprises passing the oilin a restricted stream through a heating zone and heating the sametherein to cracking temperature under pressure, dividing the heated oilissuing from the heating zone into two portions, commingling .a 0001 oilwith one of said portions and discharging the resultant mixture into avapor separating zone maintained under pressure and separating the sametherein into vapors and unvaporized oil, separately removing the vaporsand unvaporized oil and flash distilling the latter in a flashing zoneby pressure reduction, and passing the other portion of said heated oildirectly from the heating zone to the flashing zone without introductionto the separating zone.

11. The process of cracking petroleum to produce gasoline and coke whichcomprises the steps of passing petroleum products through a highpressure cracking zone, dividing the high pressure cracked products thusproduced into two streams,

one of which passes into an enlarged separating zone in which separationinto lighter and heavier products is effected, the heavier productsbeing transferred to a coking zone, the second high pressure streambeing directed into said coking zone to aid in converting said heavierproducts into coke and vapors, a cooling oil being admixed with saidfirst high pressure stream passing into said separating zone.

FRED C. KOCH.

